JP3061867B2 - Winding protector for wound core - Google Patents

Description

The present invention relates to a method for producing a winding protector for a wound core using a polymer, and in particular, to a new method of solidifying and coating the core while insulating it with a thin wall as much as possible.

Magnetic cores for electrical components are often configured as wound cores, in particular as annular wound cores. These toroids generally have a cylindrical peripheral and axial bore. Such an annular core is wound with one or more windings to produce an inductance element and a transformer.
These windings consist of insulated wires, for example enamelled copper wires. The windings must be protected against damage by the edges of the core during winding.

In particular, an annular wound core wound with a thin cut strip has very sharp edges. For annular wound cores made of amorphous or nanocrystalline alloys, additional edge protection against the forces generated during winding is also required for the inner and outer layers due to the brittleness of the band. is there. Additionally, the edge protection must be electrically insulated.

Another requirement is the stabilization and solidification of the wound core, which is a very unstable structure due to its configuration. This has little bearing on the inner and outer diameters of the annular core. This is because these dimensions are well fixed, for example by mutual point welding of the inner and outer bands. What matters here is, among other things, the height of the core. Because, for example, winding tension, band geometry, band surface shape,
This is because an axial displacement easily occurs in relation to various parameters such as a band width and the like. A wide variety of measures are known to avoid this change in core geometry.

It is generally known to pour and / or soak the core with a polymer that hardens, for example by solvent release or reaction of the two components. However, in that case, there is a drawback that the characteristic setting of the layer thickness is not possible by this method.

Many methods are known for "outer" protection of the annular core. From EP-A-0 677 856 and EP-A-0 226 793, plastics which are adapted to the outer shape of the core and whose internal solidification can be omitted by means of a self-stable configuration The case is known. German Utility Model 77 26 882
From the specification it is known to enclose the annular core in various ways with a coil which essentially prevents the enamel of the wire to be wound on the core from being damaged by the sharp edges of the core. However, this bandage winding with insulating foil requires high operating costs. This is because in an annular core the foil must always be passed through the center of the core during bandaging.

Furthermore, from EP-A-0 621 612, it is simultaneously possible to stabilize the core and to fix the thin wall and the inner side.
It is known to use shrink tubing that is shrunk in the axial direction of the core, providing protection for the outer edge.

It is furthermore known from EP 0 351 861 to spray a plastic around an annular core in a tool. Thereby, assembling and insulating parts can be manufactured simultaneously with edge protection and core solidification.

However, all known methods have the disadvantage that they require, on the one hand, very high operating costs, and, on the other hand, that they cannot be set up in particular and in particular very thin, even layers. Especially for small cores, the conventional method is to determine the difference between the outer volume (gross volume) and the magnetically used volume (net volume) due to the required wall thickness of the wrapping and the required bonding tolerances when inserting the core. This has the disadvantage that the ratio between them is undesired. The magnetic utilization (gross volume / net volume) then decreases further and deviates considerably from the theoretical ideal value of 1.

Known methods of treatment with polymers (immersion, pouring, vortex sintering, etc.) lead to considerable changes in magnetic properties. This is due to the volume change of the polymer during or after the polymerization process. The resulting shrinkage, as well as the pressure and tension, cause changes in the core properties due to the magnetostriction of the soft magnetic strip.

Accordingly, an object of the present invention is a method for manufacturing a winding protector for a magnetic core using a polymer, which hardens the winding core rationally at the same time without significantly changing the magnetic characteristics, and at the same time very thin walls. The present invention proposes a method of manufacturing a winding protection which causes insulation of the winding.

According to the invention, this problem is solved by depositing a polymer thin film from the gas phase on a magnetic core.

Typically, a polymer film is initially exposed to low pressure,
That is, it is generally produced by condensing and polymerizing monomers on the surface of a magnetic core under a vacuum. In order to generate the monomer, the oligomer is vaporized and subsequently decomposed optically and / or thermally and / or via a plasma.

A particular advantage of the polymer films deposited in this way is that, on the one hand, a gas-tight layer is already obtained from a thickness of a few μm. In addition, polymer films are distinguished by high elasticity and ductility, and thus a low risk of cracking. Monomers can penetrate very small voids in the toroid. Because they are in the middle stage of the gas phase. No action by surface forces occurs, for example during lacquering, ie no edge dewetting or bridging occurs.
Furthermore, polymer thin films deposited from the gas phase adhere very well to smooth substrates.

In one embodiment of the present invention, a polyparylene thin film is deposited as a polymer thin film. Typically, these polyparylene thin films are polyparaxylene thin films. Parylene
It is a general superclass for one family of organic polymers that arise on surfaces treated with active gas diluted at low pressure. The result is a linear crystalline polymer which has excellent properties with respect to layer thickness, is very inert towards chemicals and has no pores.

The method is particularly suitable for coating annular wound cores made of amorphous or crystalline or nanocrystalline alloys.

Typically, the core then has a fill factor of 70% to 90%. The filling factor refers to a ratio between a magnetic core cross-sectional area and a geometric core cross-sectional area.

 Advantageous embodiments are set out in the dependent claims.

Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings.

FIG. 1 is a schematic sectional view of an annular core having parylene fixed and windings, and FIG. 2 is an enlarged view of a part of FIG.

According to the drawing, an annular core 1 comprises an annular core consisting of a band 2 of an amorphous or nanocrystalline alloy. On the outer surfaces 5 and 6, the annular core is provided with a polyparaxylene coating 3.

The polyparaxylene coating 3 is deposited on the annular core 1 in a gas phase.

The coating process then starts with the heating of the powdered diparaxylene dimers, whereby they go directly to the gaseous state, ie sublimate. Process parameters include a temperature of about 150 ° C and about 1
Torr pressures have proven to be particularly suitable.

After that, gaseous diparaxylene dimer is about 690 ° C
At a temperature of about 0.5 Pa and a pressure of about 0.5 Torr (pyrolysis).

These gaseous para-xylene monomers are then directed into a process chamber, typically a vacuum chamber,
There it is evenly distributed and condenses on the surfaces 5 and 6 of the toroidal core 1 and in the cavities 7 of the banding 2 of the toroidal core 1. Thereafter, polymerization and formation of a polymer thin film are performed.

At that time, the thickness of the polymer thin film can be appropriately set by supplying para-xylene monomer. 5μ for an annular wound core
Polymer film thicknesses of m to 60 μm have proven to be particularly suitable.

Since the resulting polyparaxylene thin film has a melting point higher than 275 ° C., the annular core thus coated is surface-mounted as a component of the inductive component (SM).
A temperature-stable insulating layer is produced to withstand the requirements corresponding to the brazing process for the D part) without melting or damaging the part.

In particular, an annular winding core having an outer diameter of 2 mm to 15 mm can thus be provided with a winding protector which is coated by a drum method which is cost-effective.

In addition, such coated toroids are suitable for the manufacture of transformers and transformers where the presence of high voltages requires no partial discharge.

The polymers described herein are trademarks of Galx®
Under the name yl from Technipol of Italy
German Novatran, Grossbritannien und under ylene
Available commercially from Aipha mittels Loetsysteme, Inc.

Claims (9)

(57) [Claims] 1. A method of manufacturing a winding protector for a winding core using a polymer, wherein a polymer thin film is deposited from a gas phase on the winding core. Production method. 2. The method according to claim 1, wherein the monomer is condensed on the surface of the core under low pressure and polymerizes there. 3. The process as claimed in claim 2, wherein the oligomer is vaporized to generate the monomer and subsequently decomposed optically and / or thermally and / or via plasma. 4. The method according to claim 1, wherein a polyparylene thin film is deposited as the polymer thin film. 5. The method according to claim 4, wherein a polyparaxylene thin film is deposited as the polyparylene thin film. 6. The diparaxylene dimer is vaporized at a temperature of about 150 ° C. and a pressure of about 1 Torr, followed by about 690
Characterized in that it is thermally decomposed into para-xylene monomer at a temperature of about ℃ and a pressure of about 0.5 Torr, followed by condensation of the para-xylene monomer onto the magnetic core at room temperature and a pressure of about 0.1 Torr, where it polymerizes. Item 6. The method according to Item 5. 7. The method according to claim 2, wherein the thickness of the polymer thin film is set by supplying the monomer. 8. The method according to claim 1, wherein a winding core is provided which comprises a band of amorphous or nanocrystalline alloy. 9. The method according to claim 8, wherein the core has a fill factor of 70% to 90%.